MRI shoulder and knee- Anatomy, Scan Planning & Its Techniques

MRI shoulder and knee- Anatomy, Scan Planning & Its Techniques

1. MRI Procedure Shoulder and Knee joint

2. Shoulder joint This ball and socket joint is formed by the glenoid cavity of the scapula and the head of the humerus. The glenoid cavity is deepened by a rim of fibro cartilage ,the glenoid labrum, which provides additional stability without limiting movement. The capsular ligament is very loose inferiorly to allow for the free movement .

3. The extracapsular structure consist of : The coracohumeral ligament The glenohumeral ligament The transverse humeral ligament Muscles and movements Coracobrachialis muscle Deltoid Pectoralis major Latissimus dorsi Teres major

4. Flexion- coracobrachialis , Ant. fibres of deltoid and pectoralis major. Extension- Teres major, Latissimus dorsi and post. fibres of deltoid Abduction- Deltoid Adduction- Combined action of flexors & Extensor Circumduction - Flexors, extensors, Abductors and adductors acting in series Medial rotation- Pectoralis major , latissimus dorsi,teres major and anterior fibres of deltiod Lateral rotation- Posterior fibres of deltiod .

5. The Scapula Forms the post. part of the shoulder girdle. The anterior surface of the scapula is slightly concave and contains the subscapular fossa. The posterior surface is divided into two portions by a prominent spinous process , the crest of spine. The area above the crest is called the supraspinous fossa and the portion below it is called the infraspinous process. The teres minor from the superior 2/3 of the lateral border of the dorsal surface and major from the distal third and inferior angle.

6. Muscles of the Rotator Cuff The Supraspinatus The Infraspinatus The subscapularis The Teres minor

7. Indications Evaluation of the shoulder joint in cases of pain Instability Mass Lumps or bumps suggestive of rotator cuff disease Labral injuries Diagnosis of the impingement syndrome Frozen shoulder

8. Equipment Shoulder array /small surface coil pair or array/small flexible coil. Immobilization pads and straps Ear plugs

9. Patient Positioning Supine with arms resting comfortably by the side. Relax the shoulder to remove any hunching. Place the coil to cover the humeral head and the anatomy superior and medial to it. The patient is instructed not to move the hand during the examination.

10. Suggested protocols T1/T2 Axial T1/T2 Oblique coronal T2 Oblique sagittal Slice thickness: 3-5 mm Slice interval: 0-0.5mm

11. The Axial Protocol

12. Thin slices and thin gaps . From the top of the AC joint to below the inferior edge of the glenoid. The bicipital groove on the lateral aspect of the humerus to the distal supraspinatus muscle are included in the image. Displays joint cartilage and glenoid labrum,intra -osseous changes associated with Hills-Sachs deformity, and the condition of muscles and tendons of the rotator cuff .

13. The Coronal Protocol

14. From the infraspinatus posteriorly to the supraspinatus anteriorly and angled parallel to the supraspinatus muscle. The superior edge of the acromion to the inferior aspect of the subscapularis muscle , and the deltoid muscle laterally, and the distal third of the supraspinatus muscle medially are included on the image.

15. The Sagittal Protocol Slices are prescribed from medial to the glenoid cavity to the bicipital groove laterally. The area from the distal portion of the joint capsule to the superior border of the acromion is included in the image.

16. Abduction External Rotation excellent tool beyond the conventional 3 sequences (coronal, sagittal, and axial) for accurately assessing anteroinferior labral detachment and both partial- and full-thickness tears of the rotator cuff tendons. Placing the arm in an abducted and externally rotated position tensions the anteroinferior glenohumeral ligament and labrum. If a labral detachment is present, contrast solution defines the defect.

17. Image Optimization Technical Issues Artefact problems Patient Consideration Contrast usage

18. Shoulder Arthrography Indication:- - Partial tears - Differentiation of severe tendonitis - better delineation of the capsulolabral anatomy of the GH joint

19. Contrast Intraarticular route is selected for contrast administration 10-15 ml of solution prepared by diluting 0.2-0.4ml of Gd -DTPA into 100ml of saline.

20. Whats in the report AC joint , Acromial spur/ Osteophytes Subacromial space Rotator cuff Labral capsular complex Suprascapular notch

21. The Knee Joint The Knee is one of the most complex joints in the human body. The femur, tibia, fibula and patella are held together to provide stability for the knee joint.

22. Many patients do not have fractures but they may have torn one or more of these ligaments. This cause great pain and may later the position of the bones. The important ligaments of the knee are: 1. Posterior cruciate ligament 2. Anterior cruciate ligament 3. Tibial collateral ligament 4.Fibular collateral ligament Apart from these , the knee joint contains two fibrocartilage disks called the lateral and medial meniscus.

23. These circular menisci lie on the tibial plateaus. They are thick at the outer margin of the joint and taper off toward the centre of the tibial plateau. These menisci provide stability for the knee and also act as a shock absorber.

24. Sensitivity M. Meniscus 73-100% L. Meniscus 55-90 ACL 91-100 Specificity MM 55-97 LM 94-98 ACL 99-100

25. Indications Internal derangement of the joint (meniscal tears, cruciate ligament tears Chondromalacia patella and patella tracking Mass Instability Bone tumors and bony damage within the knee joint

26. Equipment: A transmit receive ,general purpose extremity surface coil(circumferential) Immobilization pads Ear plugs

27. Patient positioning Pt. supine on the examination couch, feet first. Knee immobilized with pads Pt. Knee positioned with slight 5-10 deg. external

28. Suggested Protocol T2 COR T1 COR STIR COR T2 SAG PD SAG T2 AX

29. Axial Protocol Thin slices/gap are prescribed. From the superior surface of the patella to the tibial tuberosity . Thin slices for patellar tracking problems and to identify chondral damage of the patella and ant. Femoral condyles.

30. Coronal Protocol Medium slices/gap are prescribed from the femoral condyles posteriorly to the anterior patella . Oriented parallel to the posterior surface of the femoral condyles.

31. Sagittal Protocol Thin slice/gap are prescribed from the lateral to the medial collateral ligament . Aligned parallel with the anterior cruciate ligament which runs at an angle. The superior edge of patella to below the tibial tuberosity are included.

32. Knee Arthrogram Indications; Evaluation of the meniscus in the Post Operative period for the assessment of the recurrent meniscal tear. Slice thickness: 3mm – 4mm. 30 – 40 ml of 1% solution of Gd -DTPA diluted with saline is injected intraarticular , followed by mild knee exercise .

33. Technical Issues SNR usually very good. The muscle , fluid and fat components of the knee give good inherent contrast. Thin slice/gap preferred since meniscal tears are suspected.(3mm slice thickness/4mm Interval)

34. Artefact problems The main source is from popliteal vessel pulsation and patient movement. Volume acquisition often result in lengthy san times and it is commom for patients to move during this time.

35. Whats in the report? Knee Joint: Joint spaces , morphology and signal intensities Evidence of joint effusion or bone marrow edema Tibia , Fibula and patella ACL, PCL , MCL, LCL morphology and S/I Medial and Lateral meniscus

36. References Handbook of MRI Technique 2 nd Edition- Catherine Westbrook CT and MRI of the Whole Body- J. Haaga Merill’s Atlas of Radiographic Positioning and Procedures- Eugene D. Frank et al Various Websites

37. Thank You Nitish Virmani Lecturer Department of Radio-Imaging Technology Faculty of Allied Health Sciences SGT University